This invention relates to oil reservoir devices for a tandem type master cylinder, which is typically usable in a dual line type oil-hydraulic brake system for automotive use and more particularly to those of the type provided with automatic oil level detector means for detecting any unusual decrease in volume of oil stored in the device and associated with an external alarm unit to energize the latter upon detection of such oil decrease.
Conventional forms of tandem type master cylinder and oil reservoir assembly, however, have generally involved such disadvantages as complexity of structure and high cost of fabrication as they have included two independent oil reservoir tanks respectively communicating with the two oil pressure chambers of the master cylinder, the two tanks being each provided with an oil filling or replenishing hole and also with means for detecting unusual fall of level of oil stored in the associated tank.